Reactivite du tetraallyletain et d'allyltrialkyletains vis a vis d'aldehydes,de cetones et d'epoxydes

Tetraallytin reacts readily with non activated ketones and exothermically with aldehydes contrary to other allylic organotins such as allytributyltin. Homoallylic alcohols are obtained after acidolysis of the adducts. Upon extended heating, allylic organotins and epoxides form products which correspond to additon products of isomeric carbonyl compounds. However, starting from cis- and trans-1-phenyl-1,2-epoxypropanes, direct regiospecific but non-stereospecific ring opening is observed with poor yields.     

Alkylation directe de cetones et d'aldehydes en presence de potasse solide en suspension

Dehydrated solid KOH, suspended in aprotic solvents, is used as a base for ketone and aldehyde alkylation. The best solvent as regards yields and selectivity is DME. The quantity of KOH depends on the carbonyl compound acidity. This method gives as good results as less convenient homogeneous conditions.     

Comportement sous impact electronique d'allenes ω-fonctionnels et des acetyleniques isomeres. Mise en evidence du transfert d'un chlore et d'un hydroxyle par un rearrangement de type mclafferty a l'aide de la spectrometrie cid-mike.

This paper describes the use of collision induced dissociation spectra in structural elucidation of C₄H₅X^+. ions, formed by chlorine or hydroxyl group migration in a McLafferty type rearrangement of the molecular ion of (ω-functionnalized allenes and their isomeric acetylenes.     

Spectres de vibration et structure d'un cristal d'amidogallate de sodium

Raman spectra (4000-150 cm^?1) of a single crystal of NaGa(NH₂)₄ and infrared spectra (4000-200 cm^?1 ) of a polycrystalline sample have been studied at different temperatures. An assignment of the bands is given. The spectra are discussed assuming S₄ and T_d point group symmetry of the Ga(NH₂)^?₄ ion at low temperature and at room temperature respectively. Metal-ligand and N-H stretching frequencies are compared to those of some other amido metalates.     

Etude de la reactivite d'ylures de sulfonium et de pyridinium stabilises par un groupement cyanoformyle

The sulfonium and pyridinium ylides stabilized by a cyanoformyl group, in an acidic medium, lead to sulfonium and pyridinium salts which are equivalents of pyridinium or sulfonium ketene salts. This originality has been used to prepare new stabilized ylides, or derivatives of substituted arylacetic acids or 4-hydroxy thiazoles.     

Heterocyclisation intramoleculaire d'alcools possedant un squelette cedranique. Oxydation par le tetraacetate de plomb et par l'oxyde de mercure et le brome

Oxidation with lead tetra-acetate of neoisocedranol yields the corresponding ether in good yield. Under the same conditions, cedrol remains unchanged; however, when cedrol is reacted with mercuric oxide and bromine, the corresponding ether is obtained as major product. The structure of the substrates is linked with the mechanism of the two reactions and with the nature of the intermediates in the heterocyclisation reaction. The difference in behaviour between the two substrates towards the two oxidising agents is rationalized.     

Reactions de l'hexafluorure de molybdene avec les aldehydes et les cetones fonctionnels

The substituents F, Cl, Br, CN, NO₂, COOR, CONR₂, P(O)R₂ do not interfere with the reaction of MoF₆ with aromatic aldehydes and ketones yielding gem-difluoro compounds, but OH, NH, OR, NR₂, CC, react preferentially with MoF₆ and prevent the reaction at CO. Yields of gem-difluoro compounds are enhanced with electron-attracting substituents on the carbonyl derivative, and are lowered when the CO group is sterically hindered. The hydrolytic stability of the RCF₂R′ compounds vary widely with the nature of R and R′. Some reactions on R and R′ leave the CF₂ group unaffected. Thus a number of new CF₂ compounds are prepared including α,α-difluoroalkyl substituted benzyl alcohol32 benzylamines34, 36 benzaldehyde27, benzoic acids24, 28, 31, 35.¹H and¹⁹F NMR data are given for all the new derivatives. The mechanism of the conversion is tentatively postulated.     

Synthese stereo et enantioselective par l'intermediare de complexes du fer de derives chrysanthemiques dieniques et d'aldehydes hemicaroniques cis et trans.

A stereo and enantioselective synthesis of cis and trans hemicaronic aldehydes, starting from the optically active sorbic aldehyde-irontricarbonyl comples, is described.